The purpose of this application is to elucidate the structural and functional bases for development of the gustatory system. The proposed project will use ultrastructural, immunohistochemical, immunocytochemical and electrophysiological approaches to correlate structure with function in developing taste buds of the rat. The rat was selected for this study because the gustatory system develops during the first few weeks after birth. Specific features of developing taste buds will be studied at selected ages, including: formation of the taste pore, types of taste cells present, time of first synapse formation and the types of taste cells involved, specificity of synaptic connections within the taste buds, immunoreactivity to antibodies directed against neuronal, growth- related and other specific proteins. The patch-clamp technique will be used to monitor the first expression and development of specific ion channels, amiloride sensitivity, and responses to chemical stimulation in developing gustatory receptor cells. The results of these studies will help answer fundamental questions regarding the development of gustation in mammals and how the nervous system interacts with taste buds during ontogeny. An understanding of the process of development in the gustatory system will also provide valuable information that may enhance our understanding of the regeneration of taste buds and other portions of the nervous system after physical trauma or disease states.